The nitric oxide synthase inhibitor N(G)-nitro-L-arginine decreases defibrillation-induced free radical generation.

Published

Journal Article

OBJECTIVES: to demonstrate that nitric oxide (NO) contributes to free radical generation after epicardial shocks and to determinethe effect of a nitric oxide synthase (NOS) inhibitor, N(G)-nitro-L-arginine (L-NNA), on free radical generation. BACKGROUND: Free radicals are generated by direct current shocks for defibrillation. NO reacts with the superoxide (O2*-) radical to for peroxynitrite (O = NOO-), which is toxic and initiates additional free radical generation. The contribution of NO to free radical generation after defibrillation is not fully defined. METHODS AND RESULTS: Fourteen open chest dogs were studied. In the initial eight dogs, 40 J damped sinusoidal monophasic epicardial shocks was administered. Using electron paramagnetic resonance, we monitored the coronary sinus concentration of ascorbate free radical (Asc*-), a measure of free radical generation (total oxidative flux). Epicardial shocks were repeated after L-NNA, 5 mg/kg IV. In six additional dogs, immunohistochemical staining was done to identify nitrotyrosine, a marker of reactive nitrogen species-mediated injury, in post-shock myocardial tissue. Three of these dogs received L-NNA pre-shock. After the initial 40 J shock, Asc*- rose 39 +/- 2.5% from baseline. After L-NNA infusion, a similar 40 J shock caused Asc*- to increase only 2 +/- 3% form baseline (P < 0.05, post-L-NNA shock versus initial shock). Nitrotyrosine staining was more prominent in control animals than dogs receiving L-NNA, suggesting prevention of O = NOO- formation. CONCLUSION: NO contributes to free radical generation and nitrosative injury after epicardial shocks; NOS inhibitors decrease radical generation by inhibiting the production of O = NOO-.

Full Text

Duke Authors

Cited Authors

  • Clark, CB; Zhang, Y; Martin, SM; Davies, LR; Xu, L; Kregel, KC; Miller, FJ; Buettner, GR; Kerber, RE

Published Date

  • March 2004

Published In

Volume / Issue

  • 60 / 3

Start / End Page

  • 351 - 357

PubMed ID

  • 15061157

Pubmed Central ID

  • 15061157

International Standard Serial Number (ISSN)

  • 0300-9572

Digital Object Identifier (DOI)

  • 10.1016/j.resuscitation.2004.02.003

Language

  • eng

Conference Location

  • Ireland